HR: 0800h
AN: S51E-1049    [Abstracts]
TI: Pn Tomography of the Central and Eastern United States
AU: * Zhang, Q
EM: qz9n9@missouri.edu
AF: Dept of Geological Sciences, Univ of Missouri at Columbia, 101 Geology Building, Univ of Missouri at Columbia, Columbia, MO 65211 United States
AU: Sandvol, E A
EM: sandvole@missouri.edu
AF: Dept of Geological Sciences, Univ of Missouri at Columbia, 101 Geology Building, Univ of Missouri at Columbia, Columbia, MO 65211 United States
AU: Liu, M
EM: lium@missouri.edu
AF: Dept of Geological Sciences, Univ of Missouri at Columbia, 101 Geology Building, Univ of Missouri at Columbia, Columbia, MO 65211 United States
AB: Approximately 44,000 Pn phase readings from the ISC and NEIC catalogs and 750 hand picked arrivals were inverted to map the velocity structure of mantle lithosphere in the Central and Eastern United States (CEUS). Overall we have a high density of ray paths within the active seismic zones in the eastern and southern parts of the CEUS, while ray coverage is relatively poor to the west of Great Lakes as well as along the eastern and southern coastlines of the U.S. The average Pn velocity in the CEUS is approximately 8.03 km/s. High Pn velocities (~8.18 km/s) within the northeastern part of the North American shield are reliable, while the resolution of the velocity image of the American shield around the mid-continent rift (MCR) is relatively low due to the poor ray coverage. Under the East Continent Rift (EC), the northern part of the Reelfoot Rift Zone (RRZ), and the South Oklahoma Aulacogen (SO), we also observe high velocity lithospheric mantle (~8.13-8.18 km/s). Typical Pn velocities (~7.98 km/s) are found between those three high velocity blocks. Low velocities are shown in the northern and southern Appalachians (~7.88-7.98 km/s) as well as the Rio Grande Rift (~7.88 km/s). In the portion of our model with the highest ray density, the Pn azimuthal anisotropy seems to be robust. These fast directions appear to mirror the boundaries of the low Pn velocity zone and parallel the Appalachians down to the southwest.
DE: 7203 Body waves
DE: 7218 Lithosphere (1236)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7270 Tomography (6982, 8180)
SC: Seismology [S]
MN: Fall Meeting 2005